1. Field of Endeavor
The present invention relates to the use of a laser optical device for optical inspection of the quality of a surface before it is coated with a layer, preferably a metallic, ceramic or organic layer.
2. Brief Description of the Related Art
Insufficient qualities of metallic or ceramic coatings on the surface of gas turbine parts, for example metallic bonding layers of thermal barrier layers, are often attributable to surface contaminations which are due to production or result from processing steps preceding the application of the metallic layer. For example, such surface contaminations may be results of the casting method or forging method, or results of the surface treatment of the unfinished part (for example, sandblasting or cleaning with organic solvents) or undesired contaminations from a previous coating stage. However, they may also simply involve dirt or oxidation products. Such contaminations are typically inspected according to the prior art by metallographic cross sections, pull-off adhesion tests or by scratch tests of the coated parts. All these methods are destructive methods and suffer from the corresponding known disadvantages.